In current optical transceivers, the transmit power of the laser transmitter is set at a fixed value between a minimum and a maximum. This fixed power setting can cause complications during installation and testing of the optical transceivers. As an example, for one type of optical transceiver, the transmit power range is between 0 and 4 dBm, and this range includes power much higher than a maximum receive power of −7 dBm. As a result, an optical attenuator needs to be inserted in the path between two optical transceivers if the optical fiber loss between the two optical transceivers is not high enough to result in the receive power being lower than −7 dBm.
Also, the amount of attenuation needed depends on the fiber loss and this requires characterization of the installed fiber before a link can be turned on. This is an additional task and requires test equipment not readily available in the field. Further still, a common practice in the field for debugging link problems is a loop back test whereby technicians put a jumper cable between the transmitter and receiver of an optical transceiver module to assure proper operation. In doing so, when an attenuator is not used and the transmitter power is at a higher power setting than the maximum receiver power, the optical transceiver module does not operate properly and in some cases the receiver can be permanently damaged.